Commonly-owned U.S. Pat. No. 7,365,470 to Eger, et al., the contents of which are incorporated herein by this reference, describes and illustrates innovative brush holder assemblies. Included as part of such a brush holder may be a brush box designed to support and restrain some movement of a brush during operation of a rotating device such as a commutator or a slip ring. In this sense the brush holder is conventional, as brush boxes generally are commonly used to support brushes.
Assemblies of the Eger patent have been well-received by users. Further innovations, nevertheless, may continue to improve their functionality, as well as functionality of other brush holders, in some circumstances. For example, brush cooling may be difficult when boxes are used, as the boxes cover much of the surface area of the brushes. Likewise brush maintenance may be difficult because of the surface-area coverage of the boxes. Conversely, because boxes do not typically extend the entire length of brushes (at least when new), they leave portions of the brushes unsupported.